HANOI, Vietnam (AP) — The U.S. declared Saturday it has a national interest in resolving disputes in Asian waters that have ignited regional tensions, as China and Japan attempted to tone down a fiery diplomatic row that has plunged the two countries’ relations to a five-year low.

U.S. Secretary of State Hillary Rodham Clinton signaled that the U.S. intended to remain a major power in the Asia-Pacific region, and waded into the spat between China and Japan that began more than a month ago, when a Chinese fishing trawler and two Japanese patrol boats collided near disputed islands.

“The United States has a national interest in the freedom of navigation and unimpeded lawful commerce,” Clinton said at a summit of East Asian leaders in Hanoi, Vietnam. “And when disputes arise over maritime territory, we are committed to resolving them peacefully based on customary international law.”

China and key U.S. ally Japan made attempts Saturday to cool down their heated dispute. Japanese Prime Minister Naoto Kan said he was able to talk briefly with Chinese Premier Wen Jiabao before the opening of the summit, but noted that a full bilateral meeting “unfortunately did not materialize this time.”

“This sort of trouble that we’re seeing right now, compared to various incidents we’ve had in the long history of our relations, would not be regarded as decisive trouble,” Kan said, adding that both countries will remain calm and work toward a solution.

The islands in the East China Sea at the center of the dispute are occupied by Japan but also claimed by China. They are called Diaoyu in China and Senkaku in Japan.

Last month’s boat collision sparked outrage in China, where anti-Japanese sentiment has long bubbled beneath the surface over Japan’s brutal World War II occupation of much of the country. The dispute, and Japan’s temporary detention of the Chinese boat captain, prompted street protests in China. Bilateral meetings were also called off and Chinese restrictions were placed on key metal exports, drawing international concern from the U.S. and elsewhere.

On Friday, it appeared there might be no meeting in Hanoi at all between the two leaders after China accused Japan of “ruining the atmosphere” for the talks.

China’s Assistant Foreign Minister Hu Zhengyue accused Japan of turning the contested islands into a “hot topic” and holding discussions with other countries prior to the conference hosted by the 10-member Association of Southeast Asian Nations, or ASEAN.

Clinton said Saturday that the U.S. is willing to host a three-way meeting with China and Japan, but it was unclear when it might be held.

“It is in all of our interests for China and Japan to have stable and peaceful relations,” she told reporters.

The U.S. has appealed for the two countries to resolve the matter peacefully but made clear it sides with Japan in the current imbroglio. After meeting with Japan’s foreign minister in Hawaii on Wednesday, Clinton said the islands are covered by a U.S.-Japan mutual security pact, although Washington takes no position on their ultimate sovereignty.

That infuriated Beijing, and on Saturday Chinese Foreign Minister Yang Jiechi warned Clinton to act with discretion and make no “wrong remarks” about the highly sensitive issue, according to a statement posted on the Foreign Ministry’s website.

Southeast Asian countries, several of which have territorial claims to islands also claimed by China, have become increasingly rattled in recent months following a number of aggressive maritime moves by the Communist giant. ASEAN on Saturday formally invited the U.S. and Russia to join its annual East Asian Summit. The inclusion of the U.S. is seen as a counterweight to help offset China’s regional might.

Clinton’s message, while couched in diplomatic niceties, was clear: China must not use its growing economic and military strength to bully its neighbors. Previous similar remarks from Clinton and other U.S. officials have drawn harsh criticism from the Chinese, who claim sovereignty over vast swaths of territory in the East and South China seas.

She praised China for taking some steps to engage with its neighbors about setting up a formal and binding code of conduct in dealing with the disputes, which extend to other strategic and potentially oil-rich islands in the region. But aides said her remarks were a signal to China that the U.S. is looking for far more.

In her comments to the summit, Clinton said the U.S. had no intention of relinquishing its role as a dominant power in the Asia-Pacific, asserting that “we will continue to leverage the strength of our bilateral relationships (and) continue expanding our emerging partnerships with a wide range of countries.”

Clinton, on a seven-country trip to Asia, will make a brief stop in China’s Hainan Island on Saturday to meet with State Councilor Dai Bingguo. The talks are intended to pave the way for President Hu Jintao’s visit to Washington early next year.